Electrical equipment is commonly installed in enclosures to protect the equipment from accidental/intentional damage, inhibit interference by unqualified and/or unauthorized personnel, and to protect nearby persons from live electrical components of the equipment.
One form of electrical equipment enclosure has a hinged door that can be opened to permit access to equipment within the enclosure or closed to prevent access to equipment within the enclosure. When closed, the door may be secured by a lock at a location remote from the hinge or hinges. In some uses, it is desirable to be able to remove the door from its hinges when the door is open, either to facilitate work on the door or on equipment mounted on the inside of the door, or because in confined areas the open door may obstruct access. However, if the door can be easily removed from its hinges when it is closed, the security provided by the lock may be bypassed.
One form of hinge that has long been popular because of its simple, robust design is a lift-off hinge consisting of a pin that is aligned along a hinge axis and mounted at one end to one of two hinged elements and a loop that fits round the pin and is mounted to the other element. In a common configuration, the pin is upright, and the bottom of the pin is mounted to a doorframe. The loop is then mounted to the door, and the weight of the door holds the loop in position on the pin. Where the door closes within the doorframe, the top of the doorframe may prevent the closed door from being lifted far enough to separate the loop from the pin. However, not all doors and doorframes can readily provide the engagement to prevent lifting off of the closed door.
A need, therefore, has existed until the present invention for a lift-off hinge that permits lifting off when in an open position but that resists lifting off in a closed position.